Determination of the Concentrations of CF 2 and CF 3 Radicals in an Argon Matrix: An Illustration Using Predicted Infrared Intensities

Abstract

A novel procedure is described for the determination of concentrations of CF₂ and CF₃ radicals from the infrared spectrum using predicted values for the absolute integrated molar absorption coefficients. The predictions were made using an F-atom polar tensor transferred from CH₃F according to procedures described earlier. These predicted intensities are used to calculate a simulated spectrum, adjusting the values assumed for the concentrations of CF₄, CF₃, and CF₂ until agreement is obtained with the experimental spectrum obtained by Milligan and Jacox from a sample of CF₂N₂ photolyzed in an argon matrix in the presence of an added F-atom source. This procedure illustrates an analytical application of predicted infrared intensities that may also be important for other unstable species.

Keywords

Infrared intensities

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The choice of Δν_1/2 = 3 cm⁻¹ is arbitrary; we made it to obtain a predicted spectrum that looks approximately like the experimental spectrum. If there is no interaction between matrix and sample, we might expect Δν_1/2 to be the same for all bands. Of course, it is likely that some interaction occurs, so that Δν_1/2 may be different for different species, or for different bands of the same species.